The original IND service lines are the modern subway's A, B, C, D, E, F and G services. In addition, the BMT's M and R now run partly on IND trackage. The Rockaway Park Shuttle supplements the A service. For operational purposes, the IND and BMT lines and services are referred to jointly as the B Division.[1]

Until 1940, it was known as the Independent City-Owned Subway System (ICOS), Independent Subway System (ISS), or Independent City-Owned Rapid Transit Railroad. It became known as the IND after unification of the subway lines in 1940; the name IND was assigned to match the three-letter acronyms that the IRT and BMT used.[1]

The first IND line was the Eighth Avenue Line in Manhattan, opened on September 10, 1932; for a while the whole system was colloquially known as the Eighth Avenue Subway. The original IND system was entirely underground in the four boroughs that it served, with the exception of a short section of the IND Culver Line containing two stations spanning the Gowanus Canal in the Gowanus section of Brooklyn.[1]

In the early 1920s, Mayor John Hylan proposed a complex series of city-owned and operated rapid transit lines to compete with the BMT and IRT, especially their elevated lines.[4][5] The New York City Transit Commission was formed in 1921 to develop a plan to reduce overcrowding on the subways. The original plans included:[1]

Two major trunk lines in midtown Manhattan, with one running under Eighth Avenue and one under Sixth Avenue, which already had an elevated line

A crosstown subway under 53rd Street (connecting with the Eighth and Sixth Avenue subways) running under the East River to Queens Plaza (Long Island City), meeting with a Brooklyn–Queens crosstown line, and continuing under Queens Boulevard and Hillside Avenue to 179th Street, where bus service would converge

The new IND Eighth Avenue Line was built using 1,000,000 cubic yards (27,000,000 cu ft) of concrete and 150,000 short tons (140,000,000 kg) of steel. The roadbed of the new subway was expected to last 30 years.[1] At the time of the line's opening, other portions of the Independent Subway System were under construction, including five underwater tunnels:[1]

There was some vandalism on the IND Eighth Avenue Line's opening day, as some of the uptown stations were broken into by people who clogged turnstile slots with gum and other objects. Two months after the IND opened for business, three exits from the 96th Street and 103rd Street stations – at 95th and 97th Streets and at 105th Street, respectively – were closed due to theft.[1]

The Queens Boulevard Line, also referred to as the Long Island City−Jamaica Line, Fifty-third Street−Jamaica Line, and Queens Boulevard−Jamaica Line prior to opening,[6][7][8] was of the original lines of the city-owned Independent Subway System (IND), planned to stretch between the IND Eighth Avenue Line in Manhattan and 178th Street and Hillside Avenue in Jamaica, Queens.[6][8][9]

The first short section of the IND Culver Line opened on March 20, 1933, taking Eighth Avenue Express A trains (and for about a month from July to August C trains) south from Jay Street to Bergen Street.[18][19] The rest of the line opened on October 7, 1933 to the "temporary" terminal at Church Avenue,[18][20] three blocks away from the Culver elevated at Ditmas Avenue.[21][22] In 1936, the A was rerouted to the IND Fulton Street Line and E trains from the Queens Boulevard Line replaced them.[18]

During construction, streetcar service along Sixth Avenue was terminated. The city had the choice of either restoring it upon the completion of construction or abandoning it immediately. As the city wanted to tear down the IRT Sixth Avenue Line right away and save on the costs of shoring it up while construction proceeded underneath it, the IRT Sixth Avenue Line was purchased for $12.5 million and terminated by the city on December 5, 1938, with the steel from the el sold to Japan.[1]

On December 15, 1940, local subway service began on Sixth Avenue from the West Fourth Street subway station to the 47-50th Street subway station with track connections to the IND 53rd Street Line.[30] The Sixth Avenue Line's construction cost $59,500,000. The following routes were added with the opening of service:

The Queens Boulevard Line was extended to Hillside Avenue and 178th Street, with a terminal station at 169th Street on April 24, 1937.[11][33][35][36] That day, express service began on the Queens Boulevard Line during rush hours, with E trains running express west of 71st–Continental Avenues, and GG trains taking over the local during rush hours.[37][38] The initial headway for express service was between three and five minutes.[39]

Mayor John Hylan proposed some never-built lines in 1922 even before the first leg of the IND was completed. These lines included:[1]

A West Side trunk line in Manhattan between 14th Street and the city limits at Yonkers. The line would be 4 tracks between 14th Street and 162nd Street, 3 tracks to Dyckman Street, and 2 tracks to the terminal. There would be a two-track spur from 162nd Street to 190th Street via Amsterdam Avenue. From 14th Street, the line would split; two tracks would connect to the BMT Canarsie Line and two tracks would continue south to a loop at Battery Park and an East River tunnel to Atlantic Avenue and Hicks Street, Brooklyn. Supposedly, there was also a plan of a line to Red Hook.

A trunk line, 4 tracks, on First Avenue from the Harlem River to 10th Street. From 10th Street, the line would split. Two tracks would run via Third Avenue and the Bowery to a new Lafayette Avenue subway in Brooklyn. The other two would run to a loop near City Hall. From the Harlem River, the line would run to 161st Street, and split into two 3-track routes: one to Fordham Road & Southern Blvd and the other to Webster Ave. & Fordham Road, where it would join the current IRT White Plains Road line and continue to 241st Street. Since this portion of the IRT El was already built to BMT clearances, and Hylan's system would consider using BMT clearances as well, all that would have to be done along this section is shave back the platforms.

A new subway line, with between two and four tracks at various areas, from approximately the Hunters Point Avenue station on today's IRT Flushing Line in Queens, heading in a southeasterly direction to Lafayette Avenue, Brooklyn. At Lafayette Avenue, the line would split. Two tracks would turn into a four-track line along Lafayette Avenue. The other two tracks would run to Flatbush and Franklin Avenues.

A 4-track subway line from Brooklyn's Borough Hall via the Lafayette Avenue subway to Bedford Avenue. From there it was three tracks to Broadway to Cypress Hills, Brooklyn where the line would continue on the present-day BMT Jamaica Line. (The line would have ended at 168th Street, where the BMT Jamaica Line once ended.) The subway would have run directly under the line along Broadway giving it direct competition for passengers, and (in Hylan's opinion) draining revenues from the BMT. Two tracks of the Lafayette Avenue subway would connect with the proposed First Avenue line.

A 4-track subway under Flatbush Avenue in Brooklyn to Nostrand Avenue, to Emmons Avenue in Sheepshead Bay, turning west onto Emmons Avenue to Surf Avenue in Coney Island. A branch of this line would head out to Floyd Bennett Field under Flatbush Avenue.

Extension of the BMT Canarsie Line to the BMT Jamaica Line somewhere beyond 121st Street in Queens.

A new line running from Prospect Avenue via Fort Hamilton Parkway, to 10th Avenue, terminating at 90th Street. BMT Culver Line trains would use this line.

A major expansion of the IND was first planned in 1929.[42] It would have added over 100 miles of new routes in Manhattan, Brooklyn, Queens, and the Bronx, merging with, intersecting or extending the existing IND rights-of way. It was claimed that this expansion, combined with the operating IRT, BMT, and IND lines, would provide subway service within a half mile of anyone's doorstep within these four boroughs.[42] Pricing—excluding acquisition and equipment costs—was estimated at US$438 million; the entire first phase had only cost US$338 million (including acquisition and equipment costs). Not long after these plans were unveiled, the Wall Street Crash of 1929 occurred and the Great Depression was ushered in, and the plans essentially became history overnight.[42] Various forms of the expansion resurfaced in 1939,[1] 1940,[43] 1951,[44]1968,[45][46] and 1998[47] but were never realized. This was the time when the IND had planned widespread elevated construction.[1]

The Court Street station on the IND Fulton Street Line was closed on June 1, 1946 due to low ridership.[49][50][51] After World War II ended, workers and materials became available for public use again. The badly needed extension to the more efficient terminal at Broadway − East New York (the current Broadway Junction station) opened on December 30, 1946.[52][53] The extension of the Fulton Street Line, the completion of which had been delayed due to war priorities, was finished by funds obtained by Mayor William O'Dwyer and was placed in operation on November 28, 1948, running along Pennsylvania Avenue and Pitkin Avenue to Euclid Avenue near the Queens border. Forty additional R10 cars were placed into service for the extension. The cost of the extension was about $46,500,000. It included the construction of the new Pitkin Avenue Storage Yard, which could accommodate 585 subway cars on 40 storage tracks.[52][54][55][56][57]

The existing 169th Street station provided an unsatisfactory terminal setup for a four track line, and this required the turning of F trains at Parsons Boulevard, and no storage facilities were provided at the station. Therefore, the line was going to be extended to 184th Place with a station at 179th Street with two island platforms, sufficient entrances and exits, and storage for four ten-car trains. The facilities would allow for the operation of express and local service to the station.[58][59] Construction on the extension started in 1946, and was projected to be completed in 1949.[59] The extension was completed later than expected and opened on December 11, 1950.[60] This extension was delayed due to the Great Depression and World War II. Both E and F trains were extended to the new station.[60][61]

On November 26, 1967, the first part of the Chrystie Street Connection opened and Sixth Avenue Line express tracks opened from 34th Street–Herald Square to West Fourth Street–Washington Square. With the opening of the connection to the Manhattan Bridge, BB service was renamed B and it was extended via the new express tracks and the connection to the West End Line in Brooklyn. D service was routed via the connection and onto the Brighton Line instead of via the Culver Line. It only ran express during rush hours. F service was extended from Broadway–Lafayette Street during rush hours, and from 34th Street during other times to Coney Island via the Culver Line.[52][69][70] On July 1, 1968, the 57th Street station opened and the portion of the Chrystie Street Connection connecting the line with the Williamsburg Bridge was opened. Service on the KK was inaugurated, running from 57th Street to 168th Street on the BMT Jamaica Line. B service was extended during non-rush hours from West Fourth Street to 57th Street. D trains began running express via the Sixth Avenue Line at all times.[71]

A month shy of twenty years after construction began, the IND 63rd Street Line went into service on October 29, 1989, after an expenditure of $898 million,[74] extending service from 57th Street with new stations at Lexington Avenue, Roosevelt Island, and 21st Street at 41st Avenue in Queens. The IND line was served by Q trains on weekdays and B trains on weekends. The 1,500-foot connector to the Queens Boulevard Line had not yet started construction.[75] The BMT line was not in use at that time. It was built for future service options, including a connection to the Second Avenue Subway for service from the Upper East Side to Lower Manhattan.

Planning for the connection to the IND Queens Boulevard Line began in December 1990, with the final design contract awarded in December 1992. Construction began on September 22, 1994.[76][77][78][79][80] The remaining section from 21st Street to the Queens Boulevard Line cost $645 million. In December 2000, the 63rd Street Connector was opened for construction reroutes.[81] The Connector came into regular use on December 16, 2001 with the rerouting of F service at all times to 63rd Street. The construction project also extended the lower level LIRR tunnel and involved a number of other elements, including the integration of ventilation plants, lowering a sewer siphon 50 feet, rehabilitation of elements of the existing line, mitigating ground water, diverting trains which continued to run through the project area and widening of the entry point to the Queens Boulevard Line to six tracks. This new tunnel connection allowed rerouting the Queens Boulevard Line F trains via the 63rd Street Tunnel, which increased capacity on the heavily-travelled Queens Boulevard Line. It also allowed a new local service, the V train, to run along the Sixth Avenue and Queens Boulevard lines; this service has since been discontinued and replaced with an extension of the M train.[74]

Sixth Avenue Line (BDFM trains): from a split from the Eighth Avenue Line at 53rd Street, two blocks east to Sixth Avenue, then south under Sixth Avenue to a junction with the Eighth Avenue Line north of Houston Street, then east under Houston Street and south under Essex Street and Rutgers Street to the Rutgers Street Tunnel to Brooklyn – parallel to the IRT Sixth Avenue Elevated

Crosstown Line (G train): from the Queens Boulevard Line at Queens Plaza, south under Jackson Avenue, Manhattan Avenue, Union Avenue, Marcy Avenue and Lafayette Avenue, coming into the middle of the Fulton Street Line and connecting south into the Culver Line

Culver Line (originally the Smith Street Line) (FG trains): from the Rutgers Street Tunnel, south under Jay Street and Smith Street, coming to the surface and turning east over the Gowanus Canal at Ninth Street, then back underground, under Ninth Street, Prospect Park West, Prospect Avenue, Fort Hamilton Parkway and McDonald Avenue, ending at Church Avenue (later extended south along the BMT Culver Line)

As originally designed, the IND train identification scheme was based on three things: the Manhattan trunk line served (8th Avenue or 6th Avenue), the northern branch line served (Washington Heights, Grand Concourse/Bronx, or Queens Boulevard), and the service level (Express or Local). The 8th Avenue routes were A, C, and E, while the 6th Avenue routes were B, D, and F. The A and B served Washington Heights, the C and D served the Grand Concourse, and the E and F served Queens Boulevard via the 53rd Street Tunnel. A single letter indicated express service, while a double letter indicated local service. In addition, G was used for Brooklyn-Queens "Crosstown" service, and H was used for any service on the extended Fulton Street (Brooklyn) line that did not originate in Manhattan.[82]

The first designations were as follows:

A

AA

Eighth Avenue – Washington Heights

BB

Sixth Avenue – Washington Heights

C

CC

Eighth Avenue – Concourse

D

Sixth Avenue – Concourse

E

Eighth Avenue – Queens Boulevard

F

Sixth Avenue – Queens Boulevard

G

GG

Brooklyn-Queens Crosstown

HH

Fulton Street

S

Special

Virtually all possibilities were used at one time or another, either in regular service or as brief special routes.[1] The "G" single-letter service was used for G service to World's Fair Station in 1939.

The final pre-Chrystie Street Connection service is shown here; for more details, see the individual service pages. Terminals shown are the furthest the service reached.[82]

After the Chrystie Street Connection opened, the original IND Service Letter scheme was gradually abandoned. All lines, whether local or express, now use a single letter, and only the 8th Avenue/6th Avenue distinction (A, C, E vs. B, D, F) has been maintained.[1]

The IND was built with longer platforms than those of the IRT or BMT. Initial plans called for stations to be built with 660 feet (200 m) long platforms to accommodate trains of eleven 60 feet (18 m) cars. However, these lengths were shortened, as stations on the IND Eighth Avenue Line between 72nd Street and 163rd Street – Amsterdam Avenue have lengths of exactly 600 feet (180 m). There were two exceptions: 96th Street was 615 feet (187 m) on both levels, as that was the standard length of platforms built for the IND after the 1940s. The 81st Street–Museum of Natural History station had an uptown platform that was 630 feet (190 m) long, and a downtown platform that was 615 feet (187 m). Platforms of exactly 600 feet (180 m) length can also be found on the IND Queens Boulevard Line between Elmhurst Avenue and 67th Avenue.[1]

Note that this is a list of New York City Subway lines, which are the physical infrastructure over which services operate.
Lines with colors next to them are trunk lines; trunk lines determine the color of New York City Subway service bullets, except for shuttles, which are dark gray.